In general, radio frequency (RF) amplifiers do not provide pure linear amplification and produce undesired spurious or intermodulation products at the amplifier output. Various techniques are implemented to improve amplifier linearity, including pre-distortion, post-distortion, and different feedback configurations. Another technique is the feed forward amplifier. Generally, a feed forward amplifier comprises directional couplers, delay lines, and amplitude control elements that are configured to cancel undesired intermodulation products. However, these distributed components result in a bulky and expensive amplifier. Additionally, a typical feed forward amplifier is operational only over a narrow band of frequencies, typically less than 10% bandwidth. In general, the bandwidth of a prior art feed forward amplifier is inherently limited by a distributed solution of the multiple couplers.
Thus, a need exists for a fully integrated monolithic solution of a feed forward amplifier. Furthermore, a need exists for a feed forward amplifier that is compact and cost effective. Also, a need exists for a feed forward amplifier that has a tunable bandwidth across a wide frequency range.